The operation and application of hay rakes and hay tedders

Categories: Zambia, ZambiëPublished On: 16th July 2019

962 words

Haymaking_1

Part 5: Components of the double rotor rake

by GJ Stoltz (Reg Eng Tech)

This month we discuss the rest of the components and features of the double rotor rake, namely the windrow screens, guide and land wheels, transport techniques and operational features.

We thank the ARC Agricultural Engineering in South Africa for making their manual on rakes and tedders available to the readers of ProAgri Zambia.

Windrow screen:

On all double rotor rakes the windrow size is controlled by an adjustable windrow screen. This feature is especially applicable to side delivery rakes, where the hay is moved from the right-hand rotor to the left-hand rotor and finally deposited at the windrow screen on the left-hand side of the machine (see Figure 1).

On double rotor rakes, the windrow screen can also be placed between the rotors to assist with the creation of the windrow (see Figure 2). The small double rotor rake has a windrow screen on each rotor. These screens are lowered and positioned close to the ground when raking is done because with these rakes the windrow is formed in the centre between the rotors (see Figure 3).

Figure 2: The windrow screen is placed between the rotors.

Figure 3: A windrow screen is placed behind each rotor.

Guide wheels and land wheels:

Some of the double rotor rakes have two land wheels at the back, mounted to the main frame in such a way that the wheels are steered from the hitch point in front. This controlled steering facility gives the rake excellent track following characteristics, allowing tight turns on headlands up to 90° (see Figure 4). Castor wheels can also be used at the back (see Figure 5).

Figure 4: One rotor, with the guide wheels, is lifted at the headland for turning. The two land wheels are steered from the hitch point and carry the whole machine all the time.

Figure 5: Castor wheels can be used at the back of the rake, and are also called “follower wheels”. They can also be locked in a straight position.

The rotors have four guide wheels for keeping the tines adjusted to the correct height. In some cases, two guide wheels are also used, but four guide wheels are used to ensure a superb raking action even at a high forward speed (see Figure 6).

Figure 6: Four guide wheels are used underneath a rotor for better contour following and smooth raking.

On small double rotor rakes, only one guide wheel is used underneath each rotor. It is a castor type wheel and is fitted with a balloon tyre. The raking height of the tines is adjusted by adjusting the wheel upwards or downwards and the wheel can also be locked in a straight position (see Figure 7).

Figure 7: Only one guide wheel is used underneath each rotor on a small double rotor rake.

Figure 8: The rotors are folded upwards for transport purposes.

Transporting techniques:

Normally no tine arm racks are mounted on the main frames of double rotor rakes, because with the big rakes the rotors are folded upwards for transporting purposes (see Figure 8). In some instances, the rotors can be positioned one after the other in order to make the rake narrower for transport purposes. All this is possible by using hydraulic cylinders that are attached to the main frame and activated from the hydraulic system of the tractor (see Figures 9 and 10). On big double rotor rakes, the rotors can be lifted partly for headland turning, or completely for road transportation.

Figure 9: The hydraulic cylinder on the side of the beam lifts the rotor partly and the cylinder on the top of the beam lifts the rotor completely in a vertical position.

Figure 10: Note the two hydraulic cylinders at the top of the main frame.

Operational features:

The double rotor rake can rake up to one hectare every 10 to 15 minutes. Where the rotors are positioned next to each other, the windrow is formed in the centre, between the two rotors. They are called centre delivery rakes. The windrow width can be between 1,2 and 1,5 metres, depending on the crop density.

This type of rake is ideal for raking windrows for big round or rectangular balers. Where these rotors are positioned next to each other, the working width can go up to 8,4 metres, and this machine can rake 6,0 hectares per hour at a land speed of 8 km/h.

The double rotor rake, with staggered rotors, can deliver a windrow between the rotors and at the same time on the left-hand side of the machine as well (see Figures 11a and 11b).

Figure 11a: Windrows are formed at the centre and left-hand side of the rake.

By adjusting the position of the rotors hydraulically, the rotors will start overlapping and a large windrow will be delivered on the left-hand side only. These machines are also called “side delivery rakes” (see Figure 12).

Figure 12: A double rotor rake delivering a windrow on the left-hand side

Figure 13: A normal size windrow is formed where there is not much material (same as with a single rotor rake).

Power requirements for double rotor rakes differ from 15 to 44 kW depending on the size of the rake. The following types of windrows can be formed with a double rotor rake:

Normal windrow (see Figure 13)
Double windrow (see Figure 14)
Multiple windrow (see Figure 15)

Figure 14: A double size windrow is formed, where the cut crop is thick enough to be used by a big baler.

Next month we shall discuss the multiple rotor rake.

Published with acknowledgement to the ARC Agricultural Engineering for the use of their rakes and tedders manual. Visit www.arc.agric.za for more information.